The Extended channel switch element is used when dot11ExtendedChannelSwitchActivated is true. The Extended channel switch element can be transmitted in an Extended Channel switch announcement frame by the Access point or in a beacon.
In addition to the regular Channel switch announcement Element parameters, the extended channel switch announcement element provides the operating class of the channel that the Access point is moving to.
When dot11SpectrumManagementRequired is true, both the channel switch announcement element and the extended channel switch element may be transmitted by the Access Point via Action frames or in the beacon.
The extended channel switch announcement Element allows an AP to change bandwidth settings of the BSS on the channel move – i.e. selecting either a 20 MHz or a 20/40 MHz bandwidth via the operating Class field of transmitted Extended Channel Switch Announcement element. The extended channel switch element is shown below
FIG COURTESY – 802.11-2012TM standard
As can be seen with the extended channel switch announcement element – the additional parameter that is included is the “New Operating Class”
The operating class determines what would be the bandwidth of the BSS after moving to the new channel. A couple of examples are shown below
Example 1
Example 2
FIG COURTESY – 802.11-2012TM standard
As can be seen from the above example – the operating class can in effect decide the operating bandwidth of the resultant channel switch operation.
Radar signals and it’s signatures